Heretofore, gas barrier films have widely been known to be produced by treating a surface of a base film with an anchor coat agent, and then depositing metal and/or metal oxide thereon.
As such gas barrier films, there has been proposed a gas barrier film obtained by providing a first overlayer based on a polyurethane polymer on at least one side of a base film made of thermoplastic resin, and further forming a second overlayer made of at least one kind of metal or metal oxide on the first overlayered layer (see, for example, the following Patent Document 1, etc.).